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Re: pg_migrator versus inherited columns

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Greg Stark <gsstark(at)mit(dot)edu>
Cc: Bruce Momjian <bruce(at)momjian(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: pg_migrator versus inherited columns
Date: 2009-07-02 00:25:56
Message-ID: 8479.1246494356@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Greg Stark <gsstark(at)mit(dot)edu> writes:
> On Wed, Jul 1, 2009 at 11:36 PM, Tom Lane<tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Comments?

> Uhm, we've had ADD INHERIT since 8.2 -- that was my first patch.

Hmm, 8.3 doesn't seem to recognize the syntax:

regression=# alter table c add inherit p;
ERROR:  type "p" does not exist
LINE 1: alter table c add inherit p;
                                  ^

> This will result in all the columns being marked attislocal. Ie, if
> they're dropped from the parent they won't be dropped automatically
> from the children any longer.

Good point.  We could have pg_dump fix that up, I suppose.  On the other
hand, I'm not entirely sure that the current dump methodology guarantees
to preserve attislocal correctly anyway.

> Frankly I never really liked attislocal -- it seems to me the user
> knows when he's dropping the column whether he wants it dropped from
> the children and should be able to explicitly request it to cascade or
> not.

The original discussions about attislocal/attinhcount came up with some
cases that seemed to make it necessary, but I've long forgotten the
details.

			regards, tom lane

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